Field of the Disclosure
The present application relates to an organic light emitting diode display device with the same.
Description of the Related Art
Recently, a variety of flat panel display (FPD) devices adapted to reduce weight and volume corresponding to disadvantages of cathode ray tube (CRT) are being developed. The flat panel display devices include liquid crystal display (LCD) devices, field emission display (FED) devices, plasma display panels (PDPs), electroluminescence devices and so on.
The PDPs have advantages such as simple structure, simple manufacture procedure, lightness and thinness, and are easy to provide a large-sized screen. In view of these points, the PDPs attract public attention. However, the PDPs have serious problems such as low light emission efficiency, low brightness and high power consumption. Also, thin film transistor LCD devices use thin film transistors as switching elements. Such thin film transistor LCD devices are being widely used as the flat display devices. However, the thin film transistor LCD devices have disadvantages such as a narrow viewing angle and a low response time, because of being non-luminous devices. Meanwhile, the electroluminescence display devices are classified into an inorganic light emitting diode display device and an organic light emitting diode display device on the basis of the formation material of a light emission layer. The organic light emitting diode display device corresponding to a self-illuminating display device has features such as high response time, high light emission efficiency, high brightness and wide viewing angle.
The organic light emitting diode display device controls a voltage between a gate electrode and a source electrode of a driving transistor. As such, a current flowing from a drain electrode of the driving transistor toward a source electrode of the driving transistor can be controlled.
The current passing through the drain and source electrodes of the driving transistor is applied to an organic light emitting diode and allows the organic light emitting diode to emit light. Light emission quantity of the organic light emitting diode can be controlled by adjusting the current quantity flowing into the organic light emitting diode.
The organic light emitting diode is proportionally stressed by the current flowing through it. Due to this, the organic light emitting diode must deteriorate and furthermore have low brightness with respect to the same current.
Also, a white organic light emitting diode can realize white by combining several color emission layers. For example, the white organic light emitting diode is formed in a multi-layered structure including yellow, green and blue emission layers. As such, when the white organic light emitting diode has been under a stress, degrees of the stress affecting the yellow, green and blue color emission layers must be different from one another. A CCT (correlated color temperature) of white must be different from a target value (or a desired value). Due to this, a residual image and an image stitch phenomenon and so on can be caused by the deterioration of the organic light emitting diode.
To address this matter, bottom-up and top-down compensation methods are being used to compensate the deterioration of the organic light emitting diode.
FIG. 1 is a data sheet illustrating a bottom-up compensation method. FIG. 2 is a data sheet is a data sheet illustrating a top-down compensation method.
Referring to FIG. 1, the bottom-up compensation method increases brightness of each pixel from an ideal value in proportion with a degree of the stress of the respective pixel. As such, power consumption must increase and the stress applied to the pixel must be weighted. Meanwhile, as shown in FIG. 2, the top-down compensation method decreases brightness of each pixel from a brightness value of a pixel, which is exposed to the greatest stress, in inverse proportion to a degree of the stress of the respective pixel. However, the top-down compensation method decreases brightness of a normal organic light emitting diode display device below a desired specification. As such, the lifespan of the organic light emitting diode display device must be reduced. Moreover, it is difficult to determine a decrement degree of the brightness for the organic light emitting diode display device.
FIG. 3 is a data sheet illustrating a CCT compensation method. As shown in FIG. 3, a blue organic emission layer of the organic light emitting diode has a shorter lifespan compared to the yellow organic emission layer of the organic light emitting diode. As such, the blue organic emission layer easily deteriorates and varies a color coordinator of the white organic light emitting diode. Therefore, a compensation of increasing brightness of the blue organic emission layer can be performed for the white organic light emitting diode. Due to this, the blue organic emission layer must be exposed to a more serious stress and the deterioration of the blue organic emission layer must be more accelerated.